Christopher James Huff wrote:
> 
>>It seems to do in case of image_maps, the case where i originally had 
>>problems with it was image_pattern (because it uses GREY_SCALE()).  This 
>>also makes it clear why using two separate images for low and high byte 
>>works.
> 
> 
> I don't know what you were using image_pattern for...the .hf feature 
> takes a vector function, almost always a pigment function. It will never 
> work with image_pattern, because pattern functions return a single float 
> value. And image_pattern won't return any sort of sensible result from a 
> red-green 16-bit data file.

Not for 24 bit tga images (which are a bad choice for heightfield data 
anyway)  If everything works as it should image_pattern in combination 
with a 16 bit grayscale format (png or pgm) would be the most elegant 
solution for this purpose:

#declare fn_Image =
   function {
     pattern {
       image_pattern {
         png "hfimage.png"
         interpolate 2
       }
     }
   }

isosurface {
   function { z - fn_Image(x, y, 0) }
   ...
}

Christoph

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